How LOFAR and wind turbines jointly found a way forward

LOFAR, which stands for Low Frequency Array, contains 25,000 antennae spread of 38 fields in the North the Netherlands. It also has stations in Germany, Sweden, France, Poland, Ireland, Latvia and the United Kingdom. LOFAR is a radio telescope that arose from the ambition of Dutch astronomers to observe the earliest moments of our universe. Queen Beatrix opened LOFAR on 12 June 2010.

Energy transition

Immediately after the opening of LOFAR, the plans for the wind farm started. At ASTRON, that came as a huge shock. The institute had worked for ten years on the construction of LOFAR, and the then Ministry of Economic Affairs had invested 100 million euros in the radio telescope. Subsequently, that same ministry would ensure that LOFAR could no longer do its work. On behalf of ASTRON, Marco de Vos explained to the then Minister of Economic Affairs, Henk Kamp, how electromagnetic radiation from the rotating turbines would disrupt LOFAR’s observations. Kamp answered that the wind turbines would still have to be placed due to the energy transition and instructed ASTRON to hold talks with the initiators of the wind farm.

Disruption of signals

Very weak signals from the cosmos are disrupted by the atmosphere and other effects, for example agglomerations in the vicinity. This disruption is nothing compared to that of the wind turbines. Due to their height, the blades of the wind turbines reflect radiation coming from various different directions, which is picked up by the antennae of ASTRON. Furthermore, the electronics in the wind turbines emit radiation that disrupts LOFAR's observations. If the radiation is at a single frequency, narrowband, ASTRON can filter this out, but that is not the case with these wind turbines. Initially, ASTRON threatened the ministry with a damages claim of millions of euros. Still, talks with the initiators of the wind farm resulted in a covenant in 2016. ASTRON could see the considerable importance of the energy transition and that it would not win a legal battle aiming for 'no wind farm'. If they had to back down, then the wind turbines would have been built without any agreement with ASTRON.

The best possible

Negotiators from ASTRON believe they achieved the best possible deal. During the talks, the policymakers and the initiators of the wind farm recognised that LOFAR's scientific capacities would suffer due to the presence of the wind turbines. This recognition was unique because ASTRON could not call upon earlier case studies. It was subsequently established that the radiation from the wind turbines had to be reduced enough to allow ASTRON researchers to still realise a large part of their scientific programme. The company Nordex designed a new type of wind turbine with an emission reduction of minus 35 dB compared to standard turbines. ASTRON was impressed by the prototype. The covenant also included the agreement that each year the turbines had to stop for fifty blocks of 12 hours and six blocks of 24 hours. ASTRON recognises that the initiators of the windfarm have incurred economic damage: these turbines are far more expensive than other turbines, and the project has been delayed by several years. In turn, ASTRON has had to relinquish part of the scientific knowledge it had aimed to gather because several parts of the LOFAR frequency band have become unusable.

Monitoring how the wind blows

An example of the science relinquished is the research into the Epoch of Reionization (EoR, a term that describes the period in which the universe was just a few hundreds of millions of years old). In anticipation of the arrival of the wind turbines, the EoR researchers could fortunately collect a lot of data beforehand over the past few years. As soon as the wind turbines become operational, researchers from other research lines will have to measure for longer periods of time to obtain the same level of quality. The impact is clear, thinks ASTRON. The wind directions will be continuously monitored, and the researchers will align their measurements with this. On windless days, the managers of the turbines will also switch off the turbines.

The future of LOFAR

ASTRON is now busy making LOFAR ready for the next ten years. This upgrade is being realised partly with an Investment Grant NWO Large and partly with compensation funding from the Ministry of Economic Affairs and Climate Policy. The upgrade includes a lot of technological innovation, new electronic systems, software and computer systems. Partners and Dutch business will also benefit from the innovation: because the manufacturing industry is building something for ASTRON, the new knowledge can subsequently be used in the telecoms industry, for example. With the projects in the field of signal processing and large datasets, the institute is inspiring software companies that collaborate at ASTRON.

Space weather

LOFAR is a highly suitable instrument for detecting charged particles that depart from the sun and cause disruptions to communication systems and electricity networks. ASTRON has convinced the ministries that the Netherlands could use LOFAR to make predictions about the harmful effects of solar activity. ASTRON researchers are specialists in developing models that support the warnings. The new research line will acquire a place in the organisation, and a group of people are studying the business aspects. However, the institute most definitely does not have the ambition of becoming a Royal Netherlands Meteorological Institute (KNMI) for space weather events, because ASTRON is of the opinion that it does not have the setup for this.

Radio astronomy in the National Strategy on Spatial Planning and the Environment

In the recent past, research with LOFAR has yielded a large stream of publications. ASTRON expects that over the next ten to twenty years, LOFAR will, within the boundary conditions, lead to fantastic new discoveries. Wind turbines are not the only disruptive influence on measurements: radio astronomy also experiences inconvenience from DAB plus, 5G and some satellites. ASTRON would like the Dutch government to state that radio astronomy, and with that LOFAR and the Westerbork telescope, are of national importance, and that future developments must therefore pay due consideration to the impact on astronomy. The National Strategy on Spatial Planning and the Environment is currently under preparation. Representatives from ASTRON have called for large scientific infrastructure, such as LOFAR, to be included in this alongside archaeological aspects and cultural heritage. Then it would be clear who needs to be consulted if something happens in the surrounding circle. ASTRON is always prepared to talk, as the coexistence with the wind farm illustrates.

Newsletter Inside NWO-I, April 2020
Text: Anita van Stel
Image: LOFAR